The cause of dramatic losses in glaciers and ice sheets in the West Antarctic is still unclear.

A recent research team has looked at ice core samples dating back between 2000 and 200 years and found that temperatures during the 1990s are comparable with similar conditions in the 1830s and 1940s. Ice cores are layered, like tree rings, and can provide information on given periods. In this case the observed decades had high traces of the oxygen 18 isotope, which relates to higher temperatures.

The team has not found enough evidence that shifts in the ice makeup can be considered exceptional given the link to El Niño effects. This makes projections difficult. The same cannot be said of the Antarctic Peninsula, which is closer to South America, where accelerated warming is much more noticeable.